Stranded Conductors
Stranded conductors are the conductors made of thin wires of small cross-section area and bunched together.they are flexible, not rigid and can be coiled very easily.
They eliminate to a large extent the dark risk of breaking through insulation.
The following points are worth noting about stranded conductors---
(1) A stranded conductor is made by twisting wires, called the strands,together to form layers.
(2) A wires of each layer are laid in helical fashion round the preceding layer.
the process is called 'Stranding' .
(3) Generally stranding is done in opposite direction for successive layers.This means if the wires of each layer twisted in left hand direction then the next layer of wires will be twisted in right hand direction , and so on.
(4) A standard stranding consist of 6 wires around one wire ,then 12 wires around the previous 6 , 18 wires around the previous 12,then 24 wires around 18 and so on.
the number of layers to be provided depends upon the number of wires to be provided.
the center wire is not counted as layer. Instead of single, 3 or 4 stranded wires may also be put in the center and over them layers may be formed. If three stranded wires are put in the center, 9 wires will be in the first layer, 15 wires will be in the second layer and so on.
The increase in the no of wires in each successive layer is 6 in each of the above cases.
Formulae for stranded conductors---
the stranded conductors are expressed as follows 7/2.24,19/2.50
where the first number 7,19 indicates total no of wires.
And the second number indicates diameter of each wire in cm.
Different types of stranded conductors are shown below------
Fig. ........ Typical three core cable with stranded conductor.
Fig....... Circular stranded conductor
Stranded conductors are the conductors made of thin wires of small cross-section area and bunched together.they are flexible, not rigid and can be coiled very easily.
They eliminate to a large extent the dark risk of breaking through insulation.
The following points are worth noting about stranded conductors---
(1) A stranded conductor is made by twisting wires, called the strands,together to form layers.
(2) A wires of each layer are laid in helical fashion round the preceding layer.
the process is called 'Stranding' .
(3) Generally stranding is done in opposite direction for successive layers.This means if the wires of each layer twisted in left hand direction then the next layer of wires will be twisted in right hand direction , and so on.
(4) A standard stranding consist of 6 wires around one wire ,then 12 wires around the previous 6 , 18 wires around the previous 12,then 24 wires around 18 and so on.
the number of layers to be provided depends upon the number of wires to be provided.
the center wire is not counted as layer. Instead of single, 3 or 4 stranded wires may also be put in the center and over them layers may be formed. If three stranded wires are put in the center, 9 wires will be in the first layer, 15 wires will be in the second layer and so on.
The increase in the no of wires in each successive layer is 6 in each of the above cases.
Formulae for stranded conductors---
the stranded conductors are expressed as follows 7/2.24,19/2.50
where the first number 7,19 indicates total no of wires.
And the second number indicates diameter of each wire in cm.
Different types of stranded conductors are shown below------
Fig. ........ Typical three core cable with stranded conductor.
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